what does the notation $x^{(n)}$ mean?












0












$begingroup$


What does the notation $x^{(n)}$ where $x$ is a matrix and $n$ is an integer?



$$|W^Tmathbf{x}^{(n)}+b-y^{(n)}|_2^2$$










share|cite|improve this question











$endgroup$

















    0












    $begingroup$


    What does the notation $x^{(n)}$ where $x$ is a matrix and $n$ is an integer?



    $$|W^Tmathbf{x}^{(n)}+b-y^{(n)}|_2^2$$










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      What does the notation $x^{(n)}$ where $x$ is a matrix and $n$ is an integer?



      $$|W^Tmathbf{x}^{(n)}+b-y^{(n)}|_2^2$$










      share|cite|improve this question











      $endgroup$




      What does the notation $x^{(n)}$ where $x$ is a matrix and $n$ is an integer?



      $$|W^Tmathbf{x}^{(n)}+b-y^{(n)}|_2^2$$







      optimization notation






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 16 at 2:01









      David M.

      1,734418




      1,734418










      asked Jan 15 at 20:11









      Ibrahim AbouhashishIbrahim Abouhashish

      367




      367






















          2 Answers
          2






          active

          oldest

          votes


















          3












          $begingroup$

          It is just an index for a sequence $x^{(1)}, x^{(2)}, x^{(3)}, ldots$, similar to $x_1, x_2, x_3, ldots$.



          The reason why they avoid subscripts $x_i$ is because presumably $x$ is a vector, so $x_i$ may be reserved for denoting "the $i$th component of the vector $x$." Using the above notation allows one to do things like $x^{(2)}_3$, which denotes the third component of the vector $x^{(2)}$ (which itself is the second element in a sequence of vectors).



          Finally, the reason for the parentheses is to differentiate it from an exponent, since "$y^2$" might look like the square of $y$.






          share|cite|improve this answer









          $endgroup$





















            3












            $begingroup$

            As I see the optimization tag, this probably means the matrix that is yielded at the $n$-th iteration step.



            In simple words, this means that $x^{(n)}$ is the $x$ matrix of your method at the $n$-th step and $y^{(n)}$ is the $y$ matrix of your method at the $n$-th step.






            share|cite|improve this answer











            $endgroup$













              Your Answer





              StackExchange.ifUsing("editor", function () {
              return StackExchange.using("mathjaxEditing", function () {
              StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
              StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
              });
              });
              }, "mathjax-editing");

              StackExchange.ready(function() {
              var channelOptions = {
              tags: "".split(" "),
              id: "69"
              };
              initTagRenderer("".split(" "), "".split(" "), channelOptions);

              StackExchange.using("externalEditor", function() {
              // Have to fire editor after snippets, if snippets enabled
              if (StackExchange.settings.snippets.snippetsEnabled) {
              StackExchange.using("snippets", function() {
              createEditor();
              });
              }
              else {
              createEditor();
              }
              });

              function createEditor() {
              StackExchange.prepareEditor({
              heartbeatType: 'answer',
              autoActivateHeartbeat: false,
              convertImagesToLinks: true,
              noModals: true,
              showLowRepImageUploadWarning: true,
              reputationToPostImages: 10,
              bindNavPrevention: true,
              postfix: "",
              imageUploader: {
              brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
              contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
              allowUrls: true
              },
              noCode: true, onDemand: true,
              discardSelector: ".discard-answer"
              ,immediatelyShowMarkdownHelp:true
              });


              }
              });














              draft saved

              draft discarded


















              StackExchange.ready(
              function () {
              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3074902%2fwhat-does-the-notation-xn-mean%23new-answer', 'question_page');
              }
              );

              Post as a guest















              Required, but never shown

























              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              3












              $begingroup$

              It is just an index for a sequence $x^{(1)}, x^{(2)}, x^{(3)}, ldots$, similar to $x_1, x_2, x_3, ldots$.



              The reason why they avoid subscripts $x_i$ is because presumably $x$ is a vector, so $x_i$ may be reserved for denoting "the $i$th component of the vector $x$." Using the above notation allows one to do things like $x^{(2)}_3$, which denotes the third component of the vector $x^{(2)}$ (which itself is the second element in a sequence of vectors).



              Finally, the reason for the parentheses is to differentiate it from an exponent, since "$y^2$" might look like the square of $y$.






              share|cite|improve this answer









              $endgroup$


















                3












                $begingroup$

                It is just an index for a sequence $x^{(1)}, x^{(2)}, x^{(3)}, ldots$, similar to $x_1, x_2, x_3, ldots$.



                The reason why they avoid subscripts $x_i$ is because presumably $x$ is a vector, so $x_i$ may be reserved for denoting "the $i$th component of the vector $x$." Using the above notation allows one to do things like $x^{(2)}_3$, which denotes the third component of the vector $x^{(2)}$ (which itself is the second element in a sequence of vectors).



                Finally, the reason for the parentheses is to differentiate it from an exponent, since "$y^2$" might look like the square of $y$.






                share|cite|improve this answer









                $endgroup$
















                  3












                  3








                  3





                  $begingroup$

                  It is just an index for a sequence $x^{(1)}, x^{(2)}, x^{(3)}, ldots$, similar to $x_1, x_2, x_3, ldots$.



                  The reason why they avoid subscripts $x_i$ is because presumably $x$ is a vector, so $x_i$ may be reserved for denoting "the $i$th component of the vector $x$." Using the above notation allows one to do things like $x^{(2)}_3$, which denotes the third component of the vector $x^{(2)}$ (which itself is the second element in a sequence of vectors).



                  Finally, the reason for the parentheses is to differentiate it from an exponent, since "$y^2$" might look like the square of $y$.






                  share|cite|improve this answer









                  $endgroup$



                  It is just an index for a sequence $x^{(1)}, x^{(2)}, x^{(3)}, ldots$, similar to $x_1, x_2, x_3, ldots$.



                  The reason why they avoid subscripts $x_i$ is because presumably $x$ is a vector, so $x_i$ may be reserved for denoting "the $i$th component of the vector $x$." Using the above notation allows one to do things like $x^{(2)}_3$, which denotes the third component of the vector $x^{(2)}$ (which itself is the second element in a sequence of vectors).



                  Finally, the reason for the parentheses is to differentiate it from an exponent, since "$y^2$" might look like the square of $y$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 15 at 20:17









                  angryavianangryavian

                  41.4k23381




                  41.4k23381























                      3












                      $begingroup$

                      As I see the optimization tag, this probably means the matrix that is yielded at the $n$-th iteration step.



                      In simple words, this means that $x^{(n)}$ is the $x$ matrix of your method at the $n$-th step and $y^{(n)}$ is the $y$ matrix of your method at the $n$-th step.






                      share|cite|improve this answer











                      $endgroup$


















                        3












                        $begingroup$

                        As I see the optimization tag, this probably means the matrix that is yielded at the $n$-th iteration step.



                        In simple words, this means that $x^{(n)}$ is the $x$ matrix of your method at the $n$-th step and $y^{(n)}$ is the $y$ matrix of your method at the $n$-th step.






                        share|cite|improve this answer











                        $endgroup$
















                          3












                          3








                          3





                          $begingroup$

                          As I see the optimization tag, this probably means the matrix that is yielded at the $n$-th iteration step.



                          In simple words, this means that $x^{(n)}$ is the $x$ matrix of your method at the $n$-th step and $y^{(n)}$ is the $y$ matrix of your method at the $n$-th step.






                          share|cite|improve this answer











                          $endgroup$



                          As I see the optimization tag, this probably means the matrix that is yielded at the $n$-th iteration step.



                          In simple words, this means that $x^{(n)}$ is the $x$ matrix of your method at the $n$-th step and $y^{(n)}$ is the $y$ matrix of your method at the $n$-th step.







                          share|cite|improve this answer














                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited Jan 15 at 20:46









                          Bernard

                          121k740116




                          121k740116










                          answered Jan 15 at 20:13









                          RebellosRebellos

                          14.8k31248




                          14.8k31248






























                              draft saved

                              draft discarded




















































                              Thanks for contributing an answer to Mathematics Stack Exchange!


                              • Please be sure to answer the question. Provide details and share your research!

                              But avoid



                              • Asking for help, clarification, or responding to other answers.

                              • Making statements based on opinion; back them up with references or personal experience.


                              Use MathJax to format equations. MathJax reference.


                              To learn more, see our tips on writing great answers.




                              draft saved


                              draft discarded














                              StackExchange.ready(
                              function () {
                              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3074902%2fwhat-does-the-notation-xn-mean%23new-answer', 'question_page');
                              }
                              );

                              Post as a guest















                              Required, but never shown





















































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown

































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown







                              Popular posts from this blog

                              'app-layout' is not a known element: how to share Component with different Modules

                              android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

                              WPF add header to Image with URL pettitions [duplicate]